In the manufacturing of flat panel displays, a panel of glass or other similar material will have numerous layers or coatings deposited thereon and stacked one upon another. The coatings are of widely different natures and act together to produce images which are visible through the glass panel. Certain of the layers of materials deposited on the glass substrate require high heat processing with temperatures in the range of 165.degree. C. to 180.degree. C. being commonly encountered; and other materials are subjected to strong chemicals such as acid in etching processes. The coatings or deposited films are extremely thin, and on the order of 2,000 to 6,500 Angstroms in thickness. The various materials which are deposited on the face of the glass substrate may include metal vapor to provide a high resolution back metal electrode with a thickness of about 1,000 Angstroms; a transparent layer of Indium Tin Oxide with a thickness of approximately 1,700 Angstroms; a transparent dielectric layer, or yttria layer with a thickness of approximately 2,000 Angstroms; a transparent light generating phosphor layer, which may be zinc sulfide doped with manganese, and with a layer of a thickness of about 6,000 Angstroms; a light emission enhancing layer such as tantalum pentoxide with a thickness of approximately 200 Angstroms; a light sink or light absorbing layer of a semiconductor compound and a thickness of about 2,500 Angstroms; and an aluminum electrode layer formed into conductive strips with a thickness of about 1,200 Angstroms; and possibly an amorphous silicon layer, and other miscellaneous electrodes and connectors.
Of course it is important, during the processing and multisteps of handling the glass substrates with the films or coatings deposited thereon, to handle the substrates carefully and in batches so that they may be easily transported from one work station to another and stored between process steps. The weight of the panels is significant because of the number and size of the panels in a batch. Simultaneous processing of 15 or more panels is regularly done.
Flat panel displays, being used as substitutes for cathoderay tubes (CRT) are rather large and may be roughly square or rectangular with sizes 12 to 18 inches at each side, or larger.
Carriers have been known in the past for handling silicon wafers in the manufacture of integrated circuit chips and such carriers are illustrated in numerous patents such as U.S. Pat. Nos. 3,961,877 and 4,471,716. Most such carriers are molded integrally in one piece and of heat resistant and chemical resistant materials such as perfluoroalkoxy otherwise known as Teflon PFA, which is a trademark of E. I. duPont deNemours & Company, Wilmington, Del. Other Teflon materials which are resistant to strong chemicals and heat include Teflon TFE which is not melt processible, but is compressed into a block and then machined to the desired shape. Certain carriers are made of cheaper plastics when not subjected to severe conditions; and there have been a few metal carriers fabricated with the use of screws connecting cast sidewall panels together with rods across the ends of the carriers to retain the sidewalls in predetermined relation to each other. Such metal carriers have been illustrated in U.S. Pat. No. 3,930,684.